Amazon has the "20th" anniversary edition. Here's a link:

http://www.amazon.com/Tron-20th-Anni.../ref=pd_cp_d_0

I too remember it as a great movie! I would have been 10 or 11 when it came out--geeze that was a long time ago... Did they have computers back then? Used to own it on "VHS" as well.

Good luck with your search!